四种还款方式的计算公式自行百度即可
按月等额本息还款法见：
/item/%E7%AD%89%E9%A2%9D%E6%9C%AC%E6%81%AF/3227456
到期还本付息法见：
/item/%E4%B8%80%E6%AC%A1%E8%BF%98%E6%9C%AC%E4%BB%98%E6%81%AF%E6%B3%95/10640616?fr=aladdin
到期还本按月付息法如下：
每次（不包含最后一次）还款金额为：出借总额×月利率
最后一次还款金额为：出借总额×月利率 + 借款总额
按四月等额本息法：
同按月等额本息是一样的，详情请看代码即可
直接上源码：
<!DOCTYPE html><html lang="zh-cn"><head><meta charset="UTF-8"><title>还款计算器</title></head><style>td{text-align:center;}</style><body><p>金额：</p><p><input type="text" value='' name="account" id='account'></p><p>年利率：</p><p><input type="text" value='' name="apr" id='apr'></p><p>期限：</p><p><select name="time_limit" id="time_limit"><option value="1">1个月</option><option value="2">2个月</option><option value="3">3个月</option><option value="4">4个月</option><option value="5">5个月</option><option value="6">6个月</option><option value="7">7个月</option><option value="8">8个月</option><option value="9">9个月</option><option value="10">10个月</option><option value="11">11个月</option><option value="12">12个月</option></select></p><p>还款方式：</p><p><select name="type" id="type"><option value="1">按月等额本息</option><option value="3">到期还本按月付息</option><option value="4">到期还本付息</option></select></p><p><button type='button' id="cal">计算</button></p><table border='1px' cellspacing="0" width='700px' id='table'></table></body><script>var account = document.getElementById('account');var apr = document.getElementById('apr');var time_limit = document.getElementById('time_limit');var typeObj = document.getElementById('type');var cal= document.getElementById('cal');var table= document.getElementById('table');var money= account.value; //借款金额var year_apr = (apr.value)/100; //年利率var period= time_limit.value;//借款期限var type = typeObj.value;//还款方式var month_apr = year_apr/12;//月利率time_limit.onchange = function(){period = time_limit.value;if(period==8){typeObj.options.add(new Option('按4月等额本息',2)); }else{typeObj.options.remove(3);}} cal.onclick=function(){money= account.value; //借款金额year_apr = (apr.value)/100; //年利率period= time_limit.value;//借款期限type = typeObj.value;//还款方式month_apr = year_apr/12;//月利率str=_cal(money,period,type,month_apr);if(str!=false){table.innerHTML=str;}}/*** @param money借款金额* @param period 借款期限* @param type还款方式 1 按月等额本息 2 按4月等额本息 3 到期还本按月付息 4 到期还本付息* @param month_apr 月利率* @return string*/function _cal(money,period,type,month_apr){var interest_tot = 0; //预期收益var repayment_tot = 0; //本息合计if(false == isNumber(money)){alert('借款金额格式错误');return false;}if(false == isNumber(month_apr)){alert('年利率格式错误');return false;}if(0 == money || money < 0){alert('借款金额不能小于或者等于0');return false;}if(0 == month_apr || month_apr < 0){alert('年利率不能小于或者等于0');return false;}var str = '<tr>\<th>期数</th>\<th>回款本息</th>\<th>回款本金</th>\<th>利息</th>\</tr>';//每月还款额 if(type == 1){repayment = (money * month_apr * Math.pow((1 + month_apr),period))/(Math.pow((1 + month_apr),period) - 1);for (var i = 1 ; i <=period ; i++) {capital= (money * month_apr * Math.pow((1 + month_apr),i - 1))/(Math.pow((1 + month_apr),period) - 1);repayment_a = repayment.toFixed(2);capital= capital.toFixed(2);interest_a = (repayment_a - capital).toFixed(2);interest_tot+=interest_a*1; //预期收益repayment_tot+=repayment_a*1//本息合计//月收本息str+='<tr>\<td>'+i+'</td>\<td>'+repayment_a+'</td>\<td>'+capital+'</td>\<td>'+interest_a+'</td>\</tr>';}str+='<tr><td colspan="4">预期收益：'+interest_tot.toFixed(2)+' 本息合计：'+repayment_tot.toFixed(2)+' 月收本息：'+repayment_a+'</td></tr>';}else if(type == 2){month_apr_new = month_apr * 4;period_new = period / 4;repayment = (money * month_apr_new * Math.pow((1 + month_apr_new),period_new))/(Math.pow((1 + month_apr_new),period_new) - 1);for (var i = 1 ; i <=period_new ; i++) {capital= (money * month_apr_new * Math.pow((1 + month_apr_new),i - 1))/(Math.pow((1 + month_apr_new),period_new) - 1);repayment_a = repayment.toFixed(2);capital= capital.toFixed(2);interest_a = (repayment_a - capital).toFixed(2);str+='<tr>\<td>'+i+'</td>\<td>'+repayment_a+'</td>\<td>'+capital+'</td>\<td>'+interest_a+'</td>\</tr>';}}else if(type == 3){interest_a = (money * month_apr).toFixed(2);for (var i = 1 ; i <=period ; i++) {capital= 0;repayment_a = interest_a;if (i == period){capital = money;repayment_a = interest_a*1 + capital*1;}str+='<tr>\<td>'+i+'</td>\<td>'+repayment_a+'</td>\<td>'+capital+'</td>\<td>'+interest_a+'</td>\</tr>';}}else if(type == 4){//贷款本金×[1+月利率（‰）×贷款期（月）] repayment = money * (1 + month_apr * period);repayment_a = repayment.toFixed(2);interest_a = (repayment_a - money).toFixed(2);str+='<tr>\<td>第'+period+'个月</td>\<td>'+repayment_a+'</td>\<td>'+money+'</td>\<td>'+interest_a+'</td>\</tr>';}else{str = '不存在';}return str;}function isNumber(val){var regPos = /^\d+(\.\d+)?$/; //非负浮点数var regNeg = /^(-(([0-9]+\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\.[0-9]+)|([0-9]*[1-9][0-9]*)))$/; //负浮点数if(regPos.test(val) || regNeg.test(val)){return true;}else{return false;}}</script></html>
常用的前端还款计算器（包括按月等额本息 按四月等额本息 到期还本付息 到期还本按月付息四种还款方式）
